Electrically powered motor vehicles typically carry batteries for supplying operating power. These batteries may periodically need to be recharged from an external power source. Recharging can be accomplished in a number of ways. The vehicle may be a purely electrically operated vehicle, so that operation is fully dependent upon charge remaining in the batteries. Alternatively, the vehicle may be a hybrid having an onboard internal combustion engine, wherein the internal combustion engine may take over from the electrical power plant or may supplement the electrical power plant by providing some of the power necessary for operation, and/or by charging the vehicle's onboard batteries. In addition, the vehicle may have a regenerative braking feature in which braking operates a dynamic brake which also functions as a generator for recharging the batteries.
Regardless of the type of vehicle or the operating scheme, commercially available electrically operated vehicles both of the purely electrical type or the so-called plug-in hybrid type, it may be necessary or desirable that the batteries be recharged while the vehicle is enroute. Such a charging need is similar to the need in a vehicle powered by fossil fuel (e.g., gas or diesel) that periodically stops at a fueling station to refill the vehicle's fuel tank(s).
Recharging of batteries suitable for powering electrically powered vehicles presents conflicting demands. It is desirable to minimize the time interval during which the vehicle is being charged. However, it is also desirable to limit voltages present during charging due to safety concerns presented by the relatively high operating voltage used in many electrically powered vehicles. It is, however, possible to recharge batteries at limited voltage by charging individual cells or groups of batteries in parallel. One approach is to separate individual cells or batteries normally series connected (to achieve the necessary high operating voltage), recharge the cells in parallel at a relatively low voltage, and then reconnect the batteries in series again. However, if the charging time is to be limited, the current must be increased accordingly.
Inductive couplings have been developed to facilitate ready battery recharging. However, inductive couplings introduce inefficiencies, notably, heating losses from induction. It is preferable to provide direct mechanical connection between charging conductors and those conductors leading to the batteries being charged to avoid inductive losses.
Batteries can be charged over long periods of time (i.e., trickle charged), for example overnight at the residence of the operator or all day at the operator's place of business. However, even the largest capacity contemporary batteries are limited as to the practical cruising range of their associated vehicles. For relatively short “out and back” trips such as commuting to a workplace, an overnight trickle charge may be sufficient to power the vehicle. However, for longer trips, it becomes very likely that many electric vehicles will have to be recharged between a departure point and a destination.
Passenger vehicles are consumer items. That is, they are typically operated by laymen, or people who are not trained in the mechanics and electrical systems of passenger vehicles. It is, therefore, necessary that any system for recharging the batteries of electrically powered vehicles be simple to operate and include inherent safety features so that consumers can safely recharge their vehicles.
It is, therefore, highly desirable to provide charging apparatus that may readily be used by ordinary motorists driving electrical vehicles. Despite relatively great size and weight which are demanded by relatively high current capacity, the charging apparatus/equipment must be reasonably easy to maneuver and inherently safe.
There exists a need for a practical way to arrange relatively expeditious, relatively safe recharging at commercial premises for operators of electrical vehicles.